A typical custard formulation, used as a control for the present invention, comprises whole milk, eggs, flour, salt and pepper. Whether sweet or savory, it is thickened by the coagulation of the egg protein. Desirably, the custard proportion should be such as to produce a cutable texture free of gumminess or graininess.
Previous work with frozen eggs and egg products has shown that cooked egg protein is not stable to freezing and thawing. In particular, toughness and excessive syneresis is exhibited by egg custards which are cooked prior to freezing and rewarmed subsequent to being frozen. The effect of the syneresis is a tendency on the part of the end product to flatten out and release fluid on standing. Sugar in the custard composition may serve as a somewhat protective agent, and sweet custards respond better to post-bake freezing then savory ones. However, excessive weeping can still be noticed.
Freezing prior to baking results in a higher quality end product but several drawbacks still remain. Freeze-thaw cycling still tends to damage the raw egg proteins by ice crystal growth and by creating microenvironmental changes; that is, eutectic mixtures with high-electrolyte concentrations which can denature the proteins. This damage will still result in some syneresis after baking and a loss of custard strength.
In addition, conventional custard compositions do not lend themselves to continuous manufacture on automotive preparation and filling lines, particularly in the case of quiche preparations which will contain particulate solids, in addition to the custard ingredients, such as meat solids, cheese solids, vegetable solids, fruit solids, or seafood solids and the like. This is because the raw custard is too thin to suspend such solids resulting in an uneven distribution of the particulates in the end product. In addition, excessive splashing is likely to occur in mechanical filling operations.
The use of gums, including natural gums or cellulosic gums to prevent the syneresis of milk or milk derived compositions is well known. For instance, prior U.S. Pat. No. 3,721,571 to Glicksman et al describes a pudding composition which exhibits resistance to syneresis under conditions of freeze-thawing or high heat treatment. The composition comprises water, sweetening agents, fat emulsions, milk solids, starch and gums, an amount of the gum being xanthan gum. The pudding composition does not contain whole eggs. Stabilizing is accomplished by the starch/gum combination.
Prior U.S. Pat. No. 3,911,144 to Strong et al describes a liquid egg product purporting to have a higher degree of freeze-thaw stability comprising an amount of egg white, nonfat dry milk solids, and other ingredients. Here again, an amount of xanthan gum is employed to impart freeze-thaw stability to the liquid egg product. A substantial amount of the product is a vegetable fat, and the proportions of ingredients are said to be such as to produce a product which has the organoleptic characteristics of whole eggs, suitable for such applications as the preparation of baked goods. Only eggs whites are employed in the product.
U.S. Pat. No. 3,993,793 to Finney is typical of those patents employing a microcrystalline cellulose as a stabilizer for ice creams and frozen confections. The compositions do not contain a substantial egg content. Another recently issued patent in this art is U.S. Pat. No. 4,216,242 to Braverman.
Prior U.S. Pat. Nos. 3,345,185, to Pisani et al and 3,510,316, to Decker, are typical of low-fat formulations usable in the preparation of frozen desserts. The formulations do not suggest the present invention.